1. Field of the Invention
The present invention relates to an image pickup apparatus that performs focusing by moving a focus lens and an image pickup element.
2. Description of the Related Art
Image pickup apparatuses such as digital still cameras and video cameras generally detect a focus state of an image-taking optical system by a phase difference detection method or a contrast detection method to perform focusing by moving a focus lens included in the image-taking optical system on the basis of the detected focus state.
Japanese Patent Laid-Open No. 2008-046417 has disclosed an image pickup apparatus that performs focusing by moving an image pickup element which photoelectrically converts an object image in addition to movement of a focus lens. This image pickup apparatus first performs a high-speed movement (coarse pitch movement) of the focus lens to obtain a focus evaluation value in the contrast detection method, and then performs a minute movement (fine pitch movement) of the image pickup element to a position at which the focus evaluation value becomes a peak value. Such a focusing operation enables high-speed and highly accurate focusing.
However, the image pickup apparatus disclosed in Japanese Patent Laid-Open No. 2008-046417 may perform insufficient focusing since a movable range of the image pickup element is narrow with respect to that of the focus lens. For example, when performing image pickup of a moving object plural times continuously, a focusing operation including movements of the focus lens and the image pickup element is repeated to follow the moving object. In the repeated focusing operations, the image pickup element repeats movement to various positions and stoppage thereat in its movable range.
In a case where image pickup is performed in a state where the image pickup element is stopped at an end of the movable range in one direction, the image pickup element can be sufficiently moved for next image pickup from the stop position in a direction opposite to the one direction, but cannot be sufficiently moved in the one direction. Therefore, the movement of the image pickup element may not be able to be used for focusing for the next image pickup.